"Above industry average in every area" when customers made purchases or upgrades over the phone

Outperformed the competition in cost of service (i.e. price of plans, additional services, and equipment)

Sprint attributed its success to improved customer experience in its retail stores, specifically the "Ready Now" program in which Sprint retail associates work one-on-one with customers to personalize their phone, set up all of its features, and demonstrate how it works before they leave the store.

For T-Mobile, this marks the wireless provider's fifth consecutive highest ranking for this particular survey. The semi-annual study has been around for eight years.

It would be a small consolation prize, but if the AT&T and T-Mobile merger does go through, then Sprint will likely find itself on top of this list alone next year.

This slightly contrasts a customer service quality survey conducted by Vocal Laboratories. The results published earlier this month found Verizon and Sprint on top of AT&T and T-Mobile with 64 and 66 percent of customers, respectively, who said they were "very satisfied" with customer service calls.

T-Mobile also recently teamed up with 7-Eleven on the same prepaid LG handset that starts at $29.99 without a contract. Pricing, rules and features will be exactly the same at Family Dollar Stores as they are at 7-Eleven.